#define _CRT_SECURE_NO_WARNINGS 1

class Solution {
public:
    vector<vector<int>> matrixBlockSum(vector<vector<int>>& mat, int k)
    {
        int n = mat.size();
        int m = mat[0].size();
        vector<vector<int>> dp(n + 1, vector<int>(m + 1));
        vector<vector<int>> answer(n, vector<int>(m));

        for (int i = 1; i <= n; i++)
        {
            for (int j = 1; j <= m; j++)
            {
                dp[i][j] = dp[i - 1][j] + dp[i][j - 1] - dp[i - 1][j - 1] + mat[i - 1][j - 1];
            }
        }

        for (int i = 0; i < n; i++)
        {
            for (int j = 0; j < m; j++)
            {
                int x1 = max(0, i - k) + 1;
                int y1 = max(0, j - k) + 1;
                int x2 = min(n - 1, i + k) + 1;
                int y2 = min(m - 1, j + k) + 1;
                //cout<<x1<<" "<<x2<<" "<<y1<<" "<<y2<<" "<<n<<" "<<m<<" "<<endl;
                answer[i][j] = dp[x2][y2] - dp[x1 - 1][y2] - dp[x2][y1 - 1] + dp[x1 - 1][y1 - 1];
            }
        }

        return answer;


    }
};